Carpenter Bees and Their Control
Carpenter Bee
Carpenter Bee Damage (center)
Photo by Jerry A Payne, Clemson University
Photo by Lamar Merck, The University of Georgia
Photos used with permission, courtesy of
www.insectimages.org
It's always interesting to get inquiries from people
about bees hovering around their decks, gutters or siding. Some are amazed
to find perfectly round 3/8" holes that look as if a vandal had done
damage.
This little "vandal" is a carpenter
bee. A carpenter bee looks similar to a bumble bee.
Here are the differences between the two:
Though carpenter bees are very large and intimidating,
unlike their wasp relatives (hornets and yellowjackets), they are not generally
aggressive. Though capable of stinging (females only), these insect don't
usual sting unless provoked. The males may hover around and intimidate
people as they pass.
Carpenter bees are very interesting in that they will
enter primarily unpainted softwoods such as pine and chew that nice, 3/8"
entry hole. After chewing a relatively short entrance, the bee will chew
another tunnel, several inches long at a
ninety degree angle to the opening. Here a female will lay eggs
starting from the back, working toward the gallery opening.
These bees
nest inside of the wood. There is one generation of these insects
annually with most of the activity in the Spring. These bees are known to
return to previously used galleries from year to year, although other bees can
make new galleries as well.
The most common sites for these intruders include
fascia board (often behind the gutters), deck railings, unpainted lawn
furniture, posts and unpainted playground equipment.
Carpenter Bee Management
Some people don't mind these insect that much. As
with other bees, they are beneficial as pollinators of flowers. However,
other people are not as happy to have carpenter bees around and seek ways to
eliminate them.
There are three ways of dealing with the problem: pesticides
and repellants and exclusion.
The most effective type of pesticide application for existing,
active Carpenter Bee galleries is dust. Unlike liquid products which are
absorbed into the porous wood, surface, dust remains on top of the wood and
available for the insect to contact. Another big advantage of dust is that the application
is targeted for this pest
within the gallery with little impact
on non target organisms such as people, pets and other animals and insects.
There are several such products available on the
market for this problem. The best are non repellent products such as carbaryl (Sevin)
dust and boric acid dust. We sell Apicide,
a carbaryl dust product and
Whitmire Perma-Dust
(aerosol boric acid dust) for those wishing to treat the problem. Either of the two
products may be applied into the entrance of an active carpenter bee galleries.
Only a small amount is needed for each gallery opening. The Boric Turbo
product is recommended for vertical openings since it will adhere to those areas
rather than falling down as the Apicide might do in such situations.
For overall control around a structure, commercial applicators are best
equipped to apply insecticides as liquids in a wettable powder formulation (a powder that suspends in water) that will repel
and kill carpenter bees. The active ingredient, cypermethrin, is
sold under the Demon WP and Cynoff WP trade names. This type of
application is helpful where there are a lot of Carpenter Bees hovering
around and targeting individual gallery opening is not practical. We do not offer
these restricted use products products for sale to the general public.
Another options is to apply a repellant called
Outlast NBS-30
which contains several plant oils that naturally repel carpenter
bees. The product can be mixed with water (works for about a week)
but for best results mix it into paint or stain (works for two years or longer). Outlast
NBS-30 should be applied to all vulnerable areas to prevent damage to the wood.
Targeting those areas where insects return year after year may be a good control
strategy.
Finally, exclusion can be used after there is clear
evidence that galleries are not longer in use. Because of the nature of
carpenter bees, it is best to seal inactive openings toward the later part of
the spring season sometime in late May or early June because carpenter bees may
deposit eggs within the galleries as summer approaches. Sealing the holes
late may result in new openings appearing as the young hatch out later
in the year or next year after over-wintering within the wood.
Exclusion includes sealing the holes with wood putty or
caulking and then painting or applying a polyurethane coating to the wood.
Note that the coatings are merely deterrents so that one cannot be certain that
bees will not attack the wood again. Where possible, wrapping wood with
aluminum flashing is the best deterrent of all. Plastic siding may be used
to cover wood siding to prevent infestation by carpenter bees. Wood-like
plastic boards may also be used in place of structural wood such as fascia to
discourage damage from carpenter bees.
Talk to us
If we have not answered your questions about carpenter
bees or if you have any questions about any pest species that you have concerns about, please contact us. We will try to
answer your inquiry promptly. If you do not receive a reply, please let us
know by resubmitting your letter. We get a huge amount of unsolicited mail
and we may accidentally overlook your inquiry. You may write
to us by clicking here, send a fax to 845-746-9018 or by calling
us
toll free number during our regular business hours, 8 am to 4 pm ET,
weekdays at 800-433-1128.
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